Compositions consisting of a bituminous component, thermoplastic polymer component, and various fillers are known in the art. They can be applied in the production of products such as below grade waterproofing, water-resistant membranes for road application, and in roofing membranes. Such compositions, however, typically require the use of solvent based bitumen mastics or application with hot bitumen, which require additional equipment not readily available to the average individual.
Heretofore fillers have been admixed with bituminous and thermoplastic polymer compositions as inactive ingredients used for decreasing cost and extending the composition. Commonly used fillers include limestone, dolomite, fly ash, silica sand, etc. For instance, U.S. Pat. No. 4,196,115 to Bresson discloses an asphalt composition with at least two different copolymers derived from a conjugated diene and a monovinyl aromatic and fillers such as silicates, carbonates, etc., and mineral aggregates such as sand, chat, pebbles or rock. These fillers play no role as an active ingredient of the composition and are therefore considered as a minor component.
The present invention addresses the current need for a cold applicable bituminous composition for roofing and paving materials with improved tack and adhesiveness. The inventive composition replaces the need for hot bituminous adhesives which create hazardous fumes, and requires expensive equipment, and also reduces the release of volatile organic compounds (VOCs) into the atmosphere found in cold application cements.
The present invention incorporates the use of fumed silica as an active ingredient in the bituminous composition. The use of fumed silica improves the composition in several areas not indicated in the prior art. As an active ingredient, the fumed silica promotes the retention of oils in the composition that, if not retained, reduce the adhesive characteristics of the bituminous composition. The interactive nature of the fumed silica promotes increased tack and adhesion of the bituminous composition. Adhesion to various substrates such as aluminum, galvanized metal, wood, and masonry is enhanced by the fumed silica. The performance (adhesion, slipping) of the present inventive composition on vertical angles at high temperatures is markedly improved over similar compositions that exclude the use of fillers or use a nonactive filler (e.g., limestone, silica sand, fly ash, etc.).